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Tony Burton and Sylvester Stallone during 'Rocky Balboa' World Premiere in 2006 at Grauman's Chinese Theatre in Hollywood, California, United States.

Tony Burton, the former boxer best known for playing Apollo Creed's trainer "Duke" in the "Rocky" franchise and featured in "The Shining," has died. He was 78.

Burton, also a former football player, appeared in the first six "Rocky" movies alongside Sylvester Stallone and Carl Weathers. Weathers responded to the news, which was confirmed by Burton's younger sister Loretta Kelly, late Thursday with a heartfelt tweet. "@E_Woodyard @TheSlyStallone Sad news. RIP Tony Burton. His intensity and talent helped make the Rocky movies successful. #BePeace," he posted.

Kelley told MLive.com that her brother had been in and out of the hospital over the past year but never received an official diagnosis. Because of his poor health condition, Kelly revealed that Burton wasn't able to see "Creed," which centered on Rocky Balboa's rival's son.

"There's a scene in the restaurant of that movie ['Creed'] where his picture is on the wall," Kelly told the Michigan publication. "We didn't talk about ['Rocky'] a lot. I mean we were excited, but other people were more excited. Whenever he would come home [to Michigan] other people would just come over."

Watch: 'Rocky' Spinoff 'Creed' Trailer

Burton graduated from Flint Northern High School in 1955, becoming an all-star football and baseball player. Before becoming an actor Burton fought professionally and won Flint Golden Gloves light heavyweight titles in 1955 and again in 1957.

He went on to appear in a couple of films in addition to the "Rocky" movies, including "The Shining," "Stir Crazy," "Assault on Precinct 13" and "The Toy."

He had been living in California with his wife, Rae, before passing away. His son Martin died of a heart attack at the age of 43 in May 2014.